A new study from Northwestern University found that pink noise may improve quality of sleep in older adults.
In the study, 13 participants 60 and older received one night of acoustic stimulation and one night of sham stimulation. The sham stimulation procedure was identical to the acoustic one, but participants did not hear any noise during sleep. For both the sham and acoustic stimulation sessions, the individuals took a memory test at night and again the next morning. Recall ability after the sham stimulation generally improved on the morning test by a few percent. However, the average improvement was three times larger after pink-noise stimulation.
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I’m one of the authors of the study. What is fundamental is not that the sound was pink noise but that the acoustic stimulation was synchronized to the brain waves of the subjects. The sound was delivered at precise moments of the oscillation of each wave that is a critical feature of this stimulation. Out of sync stimulation doesn’t improve memory.